I am a postdoc in the Department of Microbiology and Immunology, and an Instructor in the Division of Hematology. I have a long-standing interest in immunology and completed graduate work in B cell development using transgenic animal models. After my clinical training, I decided to continue in immunology, but with a change of focus to human T cell biology because of its clinical potential. To realize this goal, I joined the laboratory of Dr. Mark Davis, an internationally renowned immunologist and Director of the Stanford Institute for Immunity, Transplantation, and Infection (ITI). The presence of strong departments in chemistry, engineering and physics affords researchers at Stanford University the advantage of being able to apply the newest technologies to address biological and clinical problems. In my preliminary studies, I used peptide MHC tetramer enrichment for a novel approach: to directly isolate preimmune CD8+ T cells from blood donors. Previous studies have relied on in vitro expansion, a manipulation that may alter the cell phenotype and select for cells with a proliferative advantage. Unexpectedly, I was able to detect self-reactive CD8+ T cells at high frequency - in particular T cells recognizing preproinsulin, a type 1 diabetes (T1D) associated epitope. A gene transcript analysis by microfluidics-based qPCR suggested that self-reactive CD8+ T cells remain tolerant due to an impaired ability to clonally expand. These results show that a large pool of self-reactive T cells is normally present healthy people, and that for these cells, rather than clonal deletion, a cell intrinsic gene program may enforce tolerance. This presented an opportunity to examine human T cell tolerance and autoimmunity in the context of T1D. This proposal outlines a 5-year plan to study T cell tolerance and type 1 diabetes in people. The main hypothesis is that a large pool of self-reactive T cells exists normally in people and remains tolerant due to a common cell intrinsic gene program; in T1D, this gene program is altered in a way that increases the risk of autoimmunity. The primary goal of this project is to define a set of genes important for T cell tolerance and relevant to T1D. My long term goal is to understand how tolerance is lost in T1D and apply that knowledge to the treatment of this disease. The specific research aims are: 1) To determine a gene signature by microarray expression profiling that defines tolerance in self-reactive T cells from the blood of healthy human donors; 2) To determine the changes to a tolerance gene signature in autoimmune T cells from individuals with type I diabetes mellitus; and 3) To develop a system to test the function of candidate genes. A Mentored Career Development Award will enable me to develop into an independent and successful physician scientist. Expertise within the Davis laboratory and from external collaborations will provide a critical opportunity to acquire the technical skills necessary to execute my research aims, such as class II MHC protein expression, microarray expression profiling, and cytometry by time of flight mass spectrometry. Structured learning opportunities will allow me to improve my background in bioinformatics and expand my knowledge of advancements in human immunology. My research and/or professional development will be monitored through discussions with my mentor, regular presentations of my results to the scientific community, and a biannual meeting of a mentoring committee composed of faculty with expertise related to my aims. My long-term goal is to understand the pathogenesis of type 1 diabetes mellitus as a professor in academic medicine devoting ~90% of time to research and teaching and ~10% of time to clinical work.